AbstractBreeding for drought tolerance using novel genetic resources possessing relevant agronomic and adaptive traits is a key to enhance productivity and food security in wheat growing areas. Herein, the main objectives were (i) to use a combination scoring index (multiple scoring index, (MSI)) for selection of durum wheat genotypes under different drought stress intensities (SIs) (ii) to examine repeatability of the scoring index through bootstrap re-sample method, and (iii) to study the relationship of MSI with some drought-adaptive traits. Sixteen durum wheat genotypes were grown under rainfed and irrigated conditions during three cropping seasons (2012–2015), resulting in different drought SIs, that is, mild (SI < 0.3), moderate (0.3 < SI < 0.6), and severe (SI > 0.6). The average grain yields among test environments varied between 708 and 3631 kg ha−1. The validation of the methodology of scoring index was confirmed by the correlation coefficients between score indices and their original values across different drought SIs. According to MSI, the genotypes G16, G1, and G3 had the best combination of high productivity and high resilience to mild, moderate, and severe drought stress conditions, respectively. These results indicated that the ranking of genotypes varied among different drought SIs, which support the high potential of durum wheat for adaptation to different drought stress conditions. Based on the bootstrap samples, non-repeatable correlations were observed between the estimates of MSI from different levels of stress. The significant correlation between MSI with grain yield and 1000-kernel weight (TKW) under severe drought condition provides evidence that MSI ultimately be considered as a tool for effective selection of drought-tolerant genotypes. The MSI selected genotypes based on high productivity and resilience, to each level of drought SI, and favorable adaptive traits useful for breeding.
Phenotypic divergence for morphological and yield-related traits among some genotypes of durum wheat under drought stress and non-stress conditions
